Field-coil-insulating shield



. Sept. 2, 1924.

1. L. GRIF'F1TH FIELD COIL INSULATING SHIELD Filed Nov. 12. 1920 WITNESSES:

Awe/L. (aw/m BY A ATTORN EY MNVENTQR Patented Sept. 2. 1924.

UNITED STATES ISRAEL-L. GRIFFITH, OF WILKINSBURG,

PENNSYLVANIA, ASSIGNOB. T0 WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

FIELD-COIL-INSULATING SHIELD.

Application filed November 12, 1920. Serial No. 428,612.

To all whom it may concern:

Be it known that I, IsRAnL L. GRIFFITH, a citizen of the United States, and a resident of Wilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and useful Improvement in Field-Coil- Insulating Shields, of which the following is a specification.

y invention relates to insulators and it has particular relation to means for effectively insulating the coil members from the pole pieces in dynamo-electric machines of the salient-pole type.

One of the objects of my invention is to provide a unitary insulating member that ma be quickly and easily assembled, with a coi upon a pole piece and one that may be inexpensively manufactured as a finished article in large quantities.

Another object is to provide a device of the character described that will effectively insulate a pole piece from a coil member mounted thereon without the necessity of further insulation.

A further object is to provide an inter changeable insulating shield that may be quickly and easily removed and replaced, in the event of injury thereto.

Heretofore, it has been customary, in the manufacture of dynamo-electric machines, to separately insulate the coil members by wrapping them with tape and subsequently immersing them in a liquefied insulating compound which was permitted to harden to form a coating over the entire coil. This method was slow and expensive, by reason of the fact that'practically all of the operations were necessarily performed manually. Furthermore, it has been observed that such a method of insulating a coil member seriously interfered with the dissipation of the heat generated therein.

According to my invention, I provide uni tary insulating shields, formed of any suitable material, such as fuller board, for example, adapted to be disposed at each side of a pole piece and disposed between the same and a surrounding coil member. By employing a device of this character, it is unnecessary to wra a coil with tape or to otherwise further insulate the same. By thus permitting the bare outer surfaces of the coils to be exposed to the air or other cooling medium, a much higher rate of heat dissipation is effected.

In the accompanying drawings,

Figure 1 is a fragmentary vertical sectional view of a salient pole piece having a coil member mounted thereon and insulated therefrom in accordance with m invention.

Fig. 2 is a horizontal sectiona view, on a lar er scale, on line II-II of Fig. 1.

lg. 3 is a perspective view of a detached coil member showing the insulating shields disposed thereon.

Fig. 4 is a perspective view of an insulating shield constructed in accordance with my invention.

Referring to the drawings, 1 indicates a core of a dynamo-electric machine, preferably of built up laminated structure. The core 1 is provided with a plurality of longitudinally extending undercut recesses 2 located at spaced intervals about the periphery thereof, only one of which is shown in the drawing.

A plurality of magnetizable pole pieces 3, also preferably of laminated structure, have their inner ends provided with dove-tail extensions 4 to be suitably secured within the recesses 2. The outer ends or tips of the pole pieces 3 are provided with over-hanging head portions 5. Coil members 6, each comprising suitably coiled and uninsulated conductors, are preferably positioned upon the respective pole pieces, with the outer ends thereof abutting the head portions 5, prior to mounting the pole pieces upon the core 1.

Insulating members or shields 7, preferably of channel construction and each comprising a base portion 8 and outwardly extending flanges 9, are inserted within a coil member and disposed along each side thereof (Fig. 3) before the same is positioned upon a pole piece. The insulating shields 7 may be provided with rounded or curved ends 10 which extend slightly beyond the edges of the pole pieces and partially around the ends of the yoke portions of the coils to increase the creepage distance therebetween.

By this construction and arrangement, solid insulating'walls are provided between the pole pieces and the coils and also between the coils and the core 1. Also, by this construction, it is unnecessary to wrap or further insulate the respective coils, thus permitting the bare metal of the same to be exposed for contact with a coolin medium, for a more effective dissipation 0 heat.

My invention provides a means and construction which allows convenient accessibility to the coil when repairs are to be made thereto and which also permits a ready removal and replacement of the insulating shields for this or any other purpose.

The manner in which the coil may be re moved from the pole piece and the insulation removed from the coil is obvious.

It will be observed that the pole pieces are shown as detachably mounted on the core by a dovetailed end. They may, however, be detachably mounted on the core by any suitable fastening means. The pole pieces may, therefore, be detached from the core by disen aging the dovetailed sections from each other, or by disengaging any other fastening means employed, and lifting the pole piece from the core.

The pole piece being detached from the core, it is obvious that the coil and insulating shields may be disassembled from the pole piece by withdrawing them over the unflanged end of the pole piece.

It will be readily observed that the insulating shields, because of their size and construction, may then be conveniently detached and removed from the coil by so displacing them laterally that their flanged portions are disengaged from the coil and then withdrawing them through the open space bounded by the inner periphery of the cell.

It will be observed that the pole pieces and the coils may be ventilated and cooled by reason of radial spaces or channels 11 between the coil and the pole pieces at the opposite ends of the latter and an increased efiiciency and life of the apparatus is thereby obtained. Besides the advantages above mentioned, by the use of my invention I am enabled to effect large savings in the construction cost of apparatus to which it is applicable. This results from the cheapness of the material of which my insulation may be made and the facility with which, because of its form, it may be assembled in, and disassembled from, operative relation to the parts of the apparatus for which it is designed.

In the present state of the electrical art, apparatus to which insulators of the type herein referred to are applicable are provided with les varying in number from approximatey 40 to 90, according to the size and capacity of the apparatus. By the best electrical shop practices, the cost per pole for insulating the coil from the pole, prior to my invention, was approximately six or seven times greater than the cost of effecting as efiicient insulation of the same parts by my device and method.

It will be observed, therefore. that I have provided an insulator of such form and material that it permits quick and convenient assembly and disassembly with and from the parts with which it co-operates; that permits of convenient and ready repair of the coil or insulator itself, when desiredjthat, because of its form, permits thorough ventilation of the pole pieces and the coils; that results in a high degree of elliciency and, at the same time, in great savings and economies in the construction cost of the apparatus and which may have other advantages and results not specifically pointed out but which may herein appear.

I claim as my invention:

1. In a dynamo-electric machine, the combination with a pole piece and a coil, of an insulating member comprising a channel member of insulating material provided with extremities curved in an arc of less than 90 and adapted to be removably disposed between said coil and said pole piece.

2. In a dynamo-electric machine, the combination with a pole piece and a coil, of an insulating member comprisin a channel member of insulating material provided with extremities curved in an are less in length than one half the periphery of the end portion of said pole piece adjacent said curved extremities and adapted to be removably disposed between said coil and said pole piece.

3. In a dynamo-electric machine, the combination of a rotor core member, a pole piece detachably mounted thereon, a coil detachabl mounted on said pole piece, and a plura ity of channel members of insulating material removably disposed on opposite sides of said pole piece and between the same and said coil, said channel members being provided with extremities curved in an are less in length than one-half that portion of said coils adjacent said extremities and adapted to extend only partially around said ole piece.

4. In a dynamo-electric machine, the combination of a rotor core member, a ole piece detachably mounted thereon, a c011 detachably mounted on said pole piece, and a plurality of channel members of insulating material removably disposed on opposite sides of said pole piece and between the same and said coil, the extremities of said channel members being so spaced apart from each other as to permit said members to be readily removable.

In testimony whereof, I have hereunto subscribed my name this 27th day of October 1920.

ISRAEL L. GRIFFITH. 

